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tarp construction question

Hey guys, Im making a tarp and had a question about the center/ridgeline seam. What are some options as far as what seam to use? What do you recommend?

FYI: If you want to know what type a certain bear is, sneak up behind it and kick it. Then,
run like crazy and climb up a tree. If the bear climbs the tree and eats you, it's a black
bear. If the bear just pushes the tree over and eats you, it's a grizzly bear : )

Do not walk behind me, for I may not lead. Do not walk ahead of me, for I may not follow. Do not walk beside me, either, just leave me alone.
--unknown

Most use a flat felled seam.
Also, sew the ridgeline seam FIRST! I learned this lesson the hard way

What lessons did you learn?

I'm really curious because as an experienced user of a 'thread injector' I would plan on doing all the fine work of putting on side pullouts, hemming the sides and ends BEFORE putting together the big seam.

It's kinda like putting together a pair of pants, you sew the pockets in place, the zipper goes in before you sew the long seams!

I'm really curious because as an experienced user of a 'thread injector' I would plan on doing all the fine work of putting on side pullouts, hemming the sides and ends BEFORE putting together the big seam.

It's kinda like putting together a pair of pants, you sew the pockets in place, the zipper goes in before you sew the long seams!

If you sew the ridgeline after, one side will not be the same dimension as the other. Thats because of the way a flat felled seam is done. I am not an expert, but it was much easier after I sewed the two pieces of fabric together.

RON

A tree's a tree. How many more do you need to look at? ~ Ronald Reagan

If you sew the ridgeline after, one side will not be the same dimension as the other. Thats because of the way a flat felled seam is done. I am not an expert, but it was much easier after I sewed the two pieces of fabric together.

Actually, a felled seam offsets the ridgeline to one side of the seam no matter when you do it since the first line of sewing is the actual seam. The rest is there to hide the rough edges of the fabric and to strengthen the seam by another two lines of stitching.

Now, getting two pieces of 10 to 12' of slippery fabric to end up the same length at the end of sewing it together is the actual trick no matter how experienced you are.

One of the tricks to that is to leave the hemming of both ends to the end but to do the bottom edges and tie out stuff before you join the two panels. That way if you get the ridgeline seam a little off you can always adjust the end.

Actually, a felled seam offsets the ridgeline to one side of the seam no matter when you do it since the first line of sewing is the actual seam.

If you match the edges first, then sew the first line, THEN cut the top edge to provide the area to fold over the bottom edge, you will get an offset ridgeline.

But...

...if you offset the top edge by 1/4 - 1/2 inch (depends on your fold) BEFORE you sew your first line, sew that line, THEN fold the bottom over for your final line, you will get an even ridgeline to both sides of the tarp. It seems weird but it works. I just finished mine a few days ago and the dimensions were exact.

To the OP, another option is...
To make sure no problems at the ridgeline, I'm making a tarp by cutting one side in half, lengthwise. Then sewing the half parts to the uncut piece.
This makes two seams, but if there is a failure it is not above me, but halfway down the tarp, yikes.

I'm not familiar with the french seam-------what is it and what are the advantages? Disadvantages?

FYI: If you want to know what type a certain bear is, sneak up behind it and kick it. Then,
run like crazy and climb up a tree. If the bear climbs the tree and eats you, it's a black
bear. If the bear just pushes the tree over and eats you, it's a grizzly bear : )

Do not walk behind me, for I may not lead. Do not walk ahead of me, for I may not follow. Do not walk beside me, either, just leave me alone.
--unknown

i was worried about an "under tarp ridge line" chaffing the mat'l so i over lapped both sides,by about 1.5>2" and had a seam on each side of the ridge line. that way no seam is on top, but it's double thickness where there are higher stresses. i have since moved away from the under tarp line to end pulls, still wil the extra mat'l there i feel comfortable pitching it as taut as i feel like.